Why your weight-loss app doesn’t work – and why that matters

There are few things worse than being an obesity scientist at a holiday party. Once they learn my profession, most people skulk away, often hiding their food in the process. The brave few who remain often lean closer and quietly ask for the “secret” to weight loss – as if we scientists were a “DaVinci Code”-style cabal devoted to suppressing the true “secret” to dieting.

Lately, however, I’m hearing different questions. Instead of asking about the best weight-loss program, my interrogators increasingly ask about the best app. My answer is often unsatisfying: Most apps don’t work.

I’ve been studying weight loss for more than a decade, during which we’ve seen tremendous shifts. A decade ago, American dieters tended to join a gym, buy a book or join a commercial weight-loss program. Now many use one of thousands of weight-loss apps. Estimates suggest the top 10 weight-loss apps have been downloaded well over 300 million times.

Yet there’s little evidence these apps will help you lose much weight. Sure, some people have used them successfully, but few apps have ever been tested in a scientific study. Those that have been tested either show poor results, or show better results only when combined with support from a dietician or health coach. We know little about how well most apps work on their own – the way most people likely use them.

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Most of us would never take a medication that hadn’t been deemed effective in a clinical trial. Yet we have few qualms about using apps with no scientific basis – often developed by people without scientific training – to significantly change what we eat, drink and do.

Many apps include some components backed by strong science, such as calorie tracking. Yet they rarely include most of the tools and strategies that high-quality weight loss treatments employ. In fact, most weight-loss apps include less than 10 percent of the elements scientists recommend for optimal weight-loss outcomes. That’s in contrast to leading weight-loss programs, many of which are based on good scientific evidence.

What’s the risk of using a weight-loss app that doesn’t work? It probably won’t hurt you physically. The impact on motivation is another story, though. When we “fail” at weight loss, most of us don’t blame the program, we blame ourselves. Yet the real problem may be the app.

Fortunately, a second generation of more promising apps is starting to hit the market. Some are built with expert guidance and tested in clinical trials. If you’re interested in picking an app with the best chance of helping you lose weight, look for all four of these things – I call them “the four S’s.”

▪ Skills: Most of us know what to do to lose weight – eat less, move more. But how do you handle eating when you're away at a conference? How do you resist stress eating, and avoid getting off track on weekends? What should you do when you overindulge? The best apps teach strategies to help you lose weight.

▪ Support: Good evidence suggests people do better with weight loss when they’re supported. While support from a close friend or family member can help, support from a dietitian, psychologist, health coach or other health expert is much better. Support can also come from software designed to give personalized feedback about weight-loss efforts. The best apps either link you with supporters or use advanced artificial intelligence to mimic human support.

▪ Self-monitoring: This is critical to behavior change. Tracking calories is best, but tracking weight, foods or activities can also work. Consistency is key – people who track reliably five to seven times each week succeed best with weight loss.

This last point bears emphasizing. Scientists have learned a lot about what it takes to lose weight. The makers of your app should be able to point to scientific research as the basis of their program.

If they can't, move on.

Gary Bennett is a professor of psychology and neuroscience at Duke University, director of the Duke Obesity Prevention Program and president of the Society of Behavioral Medicine.